Conventional turbomachines, such as turbines, compressors, and compact motor-compressors, are often utilized in a myriad of applications and industrial processes that expose the turbomachines and/or components thereof to extreme operating conditions (e.g., high temperatures and mechanical stress). Accordingly, the turbomachines and/or components thereof are often fabricated from materials, such as metals and alloys, which provide the required strength and stiffness to endure these extreme operation conditions. For example, conventional turbomachines and/or components thereof are often fabricated from carbon and stainless steels, which provide high tensile strength, ductility, and stiffness.
As advancements are made in these industrial processes, however, production requirements for the turbomachines are often heightened. In many cases, to meet the heightened production requirements, the size or dimensions of the turbomachines and/or components thereof are often increased. Increasing the size of the turbomachines and/or components thereof, however, results in a corresponding increase in mass due to the high density of the metals and alloys, which may be detrimental to efficient operation and production in the turbomachines. Additionally, increasing production may require subjecting the turbomachines and/or components thereof to higher operating temperatures and/or mechanical stresses. Accordingly, the materials used to fabricate the turbomachines and/or components thereof must be capable of enduring the higher operating temperatures and/or mechanical stresses.
In view of the foregoing, attempts have been made to discover or create lightweight materials having properties (e.g., strength and/or stiffness) that meet or exceed those of metals and alloys. These attempts have resulted in the development of composite materials, such as metal matrix composites. Metal matrix composites may include a metal matrix having one or more reinforcing materials dispersed therein. The properties of the metal matrix composites may be tailored by modifying the metal matrix and/or the reinforcing materials. For example, to fabricate a metal matrix composite having a low density and high strength, a low density metal, such as aluminum, may be combined with a high strength reinforcing material, such as carbon fibers. Recently, attempts have been made to utilize carbon nanotubes as the reinforcing material, due to the improved mechanical properties they exhibit over other materials, such as carbon fibers. However, the majority of these attempts have not been successful or have resulted in composite materials with properties that are inadequate for industrial applications. Further, these attempts often provide metal matrix composites where the carbon nanotubes are randomly dispersed therein, thereby providing composite materials with only isotropic properties.
What is needed, then, are methods for fabricating carbon nanotube metal matrix composites having carbon nanotubes aligned or substantially aligned and homogenously dispersed therein, thereby providing the carbon nanotube metal matrix composite with anisotropic properties.